1. Field of the Invention
The present invention relates to aneurismal treatments. More particularly, the present invention relates to methods for contracting and shrinking aneurysms.
2. Description of the Related Art
Vascular aneurysms are the result of abnormal dilation of a blood vessel, usually resulting from disease and/or genetic predisposition, which weakens the arterial wall and allows it to expand. The weakened areas of the arterial wall caused by an aneurysm are problematic because they are subject to rupture and if a rupture occurs, the aneurysm can prove fatal.
In the prior art, several procedures and methods have been established for the exclusion of aneurysms. One such method involved the insertion of a coil within the aneurysm itself. Using prior art coil insertion methods, the coil precipitated the formation of a thrombus, or clot, within the aneurysm. The thrombus then partially, or completely, occluded the aneurysm. In this manner, blood from the parent artery (or vessel) was prevented from flowing into, and circulating within, the aneurysm. Consequently, pressure on the weakened arterial wall at the aneurysm site was reduced, as was the risk of rupture.
While at times an effective treatment, the prior art coil insertion method suffered from several drawbacks. First, there was a risk of the coil, or ensuing thrombus, migrating from the aneurysm to the parent artery or vessel and causing a thrombo-embolic stroke. To minimize this risk, the prior art coil insertion method was typically limited to the treatment of saccular aneurysms having small necks to ensure that, once inserted, the coil remained within the aneurysm. In addition, wide-necked and fusiform aneurysms were also difficult to treat effectively with prior art coil insertion methods. Another disadvantage of prior art coil insertion methods was that the coils could rupture the aneurysm by poking through the aneurysm wall, resulting in life-threatening subarachnoid hemorrhage.
In addition, the effectiveness of the prior art coil insertion method discussed above was limited by the fact that while the insertion of the coil, and the resulting thrombus, could result in protecting the arterial wall at the aneurysm site, the method did not promote shrinkage of the aneurysm, or in any way address the expansion of the arterial wall at the aneurysm site.
One common result using prior art methods was compaction of the coils within the aneurysm within the 3-month follow-up period. If left untreated, the aneurysm could then continue to enlarge, and the risk of rupture remained. By not shrinking the aneurysm, prior art coil insertion methods often resulted in the coils ending up contributing to the “mass effect”, in which the aneurysm pressed against adjacent structures such as cranial nerves, other vessels, and the brain parenchyma.
In short, the prior art coil insertion method treated the symptom but did nothing to provide a cure, or partial cure, for the expansion of the arterial wall at the aneurysm site.
In addition, since the coils used with the prior art coil insertion method had to be of a minimum size, typically three millimeters or more, to perform their function and, since the coils had to be inserted into the aneurysm site, the prior art method could only be used on relatively large aneurysms, i.e., aneurysms having diameters of three millimeters or more. Therefore, the prior art coil insertion method typically could not be used on smaller aneurysms, such as those that might be advantageously found by early detection. Consequently, in the prior art, many aneurysms had to be either treated by more intrusive, and potentially dangerous, methods or, in some cases, the patient would simply have to wait until the aneurysm was large enough to allow treatment using the prior art coil insertion method. Since, as discussed above, aneurysms can result in a rupture of the arterial wall, and possibly death, waiting for the aneurysm to expand before treating it was not a desirable situation.
In addition to prior art coil insertion methods for excluding aneurysms, other prior art methods have been established for the exclusion of aneurysms including the use of liquid embolics such as MTI's Onyx and the various methacrylates. However, like the prior art coil insertion methods, these other prior art methods treated the symptom but did nothing to shrink the aneurysm or provide a cure, or partial cure, for the expansion of the arterial wall at the aneurysm site.
What is needed is a method for treating aneurysms of all sizes that promotes shrinkage of the aneurysm in addition to strengthening of the arterial wall at the aneurysm site.